Membrane PotentialsMembranesMyocardiumSarcolemmaCell MembraneNitrendipineHeartDihydroalprenololReceptors, AdrenergicMembrane Potential, MitochondrialIsoproterenolIntracellular MembranesReceptors, Adrenergic, betaGuinea PigsMembrane LipidsMyocytes, CardiacAdenylate CyclaseHeart VentriclesMyocardial ContractionKineticsMembranes, ArtificialPotassiumCalciumCell Membrane PermeabilityCardiac OutputMitochondriaErythrocyte MembraneMembrane FluidityElectrophysiologySodiumAction PotentialsElectric ConductivityArrhythmias, CardiacTime FactorsPatch-Clamp TechniquesBasement MembraneMitochondrial MembranesIon ChannelsCardiac Surgical ProceduresCells, CulturedValinomycinPotassium ChannelsDeath, Sudden, CardiacHydrogen-Ion ConcentrationMembrane Transport ProteinsAdenosine TriphosphateChloridesModels, BiologicalNeuronsCell LineRats, Sprague-DawleyLipid BilayersFluorescent DyesMembrane GlycoproteinsMicroscopy, ElectronBiological Transport, ActiveTrityl CompoundsCarbonyl Cyanide p-TrifluoromethoxyphenylhydrazoneProtein TransportRabbitsElectric StimulationApoptosisCarrier ProteinsCarbonyl Cyanide m-Chlorophenyl HydrazoneOuabainRats, WistarSynaptic MembranesCardiac Pacing, ArtificialDose-Response Relationship, DrugCardiomegalyMicroelectrodesIon Channel GatingDogsLiposomesTetrodotoxinCardiac TamponadeMutationMicroscopy, FluorescenceHeart DiseasesProtein BindingSignal TransductionMolecular Sequence DataCardiac CatheterizationCarbocyaninesMicroscopy, ConfocalCalcium ChannelsReactive Oxygen SpeciesBariumSodium-Potassium-Exchanging ATPasePotassium Channel BlockersPermeabilityTemperatureOnium CompoundsProtein Structure, TertiaryHeart ArrestCell FractionationAmino Acid SequenceNigericinCalcium SignalingCytosol